UMassage: Self Back Massager [University of North Carolina at Chapel Hill]

Matthew Boehm, Michael Bradley, Jason Cooper

Abstract

UMassage was designed for a client displaying symptoms of fibromyalgia in her lower and upper back.  The best treatment for fibromyalgia is deep muscle massage.  Although the client has tried many different massage techniques, most of them cannot adequately reach the affected areas of her back.  Additionally, the client spends much of her day in her car for work, and thus she needs a portable massaging solution.  We developed a back massager that is lightweight, durable, and portable.  It allows the user to manipulate the force and position of the massager head while comfortably keeping his/her arms in front of his/her torso. The massager reaches all areas of the lower and upper back and provides multiple massage modes via interchangeable attachments.  The client evaluated the device over a period of a week, and found that the device met all of her requirements in being able to comfortably massage the hard-to-reach problem areas of her back.

Introduction/Background

Fibromyalgia is a disorder involving widespread musculoskeletal pain, which may also cause fatigue, sleep, memory, and mood issues [1].  Although there isn’t much research available as to why fibromyalgia occurs, it is believed that the disorder amplifies painful muscle sensations by affecting the way in which the brain perceives pain signals.  Fibromyalgia may be caused by either a singular event involving significant stress or physical trauma, or by the long-term accumulation of symptoms.

Our client is a middle-aged woman who has symptoms that are consistent with fibromyalgia in her lower back, upper back, and shoulders.  She used to be an employee of the US Postal Service, and thus had to undergo repetitive strenuous motion to her legs and back for many years.  She had to leave the job back in 2006, when a series of back injuries (first her lower back, and later her upper back) prevented her from delivering mail.  These injuries, in conjunction with her daily chores that involve bending, have caused major back pain for the client, to the point that she has difficulty sleeping.  Additionally, the client’s current profession involves driving cars to and from car dealerships in other counties.  This profession causes her to have to sit still for long periods of time, as well as walk fairly long distances to cars.  Both of these activities cause her to experience pain and discomfort in her legs and back.

Currently, the only treatment for fibromyalgia is muscle massaging.  Although there are several forms of muscle massagers on the market, such as massage chairs, hand-held massagers, and even a simple tennis ball massage method, these methods are either inconvenient for the patient or they do not entirely affect the muscle areas of need [2-3].  The client’s current treatment for fibromyalgia involves dancing and doing exercise to warm up her muscles after waking up, followed by back and leg stretches.  This method keeps her muscles feeling limber until she begins to do repetitive strenuous tasks, such as washing dishes or walking long distances.  Her best solution is using her Whirlpool Jacuzzi, which gives her the most even and comfortable massaging experience.  However, it is inconvenient for the client to be using the Whirlpool several times per day, so a more portable yet equally effective solution was necessary.

Problem Statement

The client needs a portable massaging solution that can reach the problematic areas of her back.  Thus, the goal is to design a device that can be used comfortably and without excessive reaching, all while maintaining mechanical durability and minimizing device weight.

Design and Development

To accomplish our goal, we created a device that consists of an ergonomic frame with massaging attachments, which allows the user to manipulate the attachment from the front of the body.  The user holds the device around his/her back, holding both handles in front of his/her body.  They can then position the attachment against the problematic area and apply pressure or other necessary motion to relieve pain.  The wide design allows the user to reach all areas of the back by adjusting the position of the frame around the body.  The attachment mount provides an area for the user to connect and disconnect a variety of massaging attachments quickly and easily to create an assortment of massaging sensations.  The device was made into two models: a Standard Model for home use and a Travel Model for greater portability.

Standard Model Frame:

The frame was constructed from a single 6 foot length of 1 inch furniture-grade PVC pipe. PVC was used for its durability, light weight, and availability of standardized connectors.  A heat gun was used to soften the pipe in increments and shape the frame according to a stencil drawn on the floor.  Use of a stencil allowed for consistent and symmetrical frame construction.  Heat shrink rubber grips were added to the handle portion of the frame to increase comfort and handling.

Travel Model Frame:

Figure 1: Travel Model Assembled

Figure 2: Travel Model Disassembled

To create the travel frame, a standard frame was shaped and then cut in half.  A 6 inch length of ¾ inch PVC pipe was inserted 3 inches into one half of the frame. This was done by heating up the larger piece until the PVC was flexible enough to allow for the ¾ insert to slide in easily.  This left an exposed 3 inches of ¾ PVC acting as a male insert, which plugs into the opposite half to reassemble the frame.  Rubber grips were also added to this frame.

Attachment Mount:

Figure 3: Standard Model Attachment Mount with Attachments

Figure 4: Travel Model Attachment Mount

In the Standard Model of the device, the attachment mount was created using a ¾ inch x 1 inch PVC threaded snap tee.  The tee was attached at the center of the frame back piece with two ¼ inch screws that were inserted in holes through the tee and frame tube.  The threaded tee allows for the individual massaging attachments to be connected to the frame.

For the Travel Model the attachment mount served the purpose of securing the two halves of the frame, allowing for collapsibility, and also functioned as the connection point for the various massage attachments.  Like in the Standard Model, it was made using a ¾ inch x 1 inch PVC threaded snap tee.  The tee was clipped over the joint between the frame halves and was permanently secured on the male end of the frame using a single ¼ inch screw fastened with acorn nuts.  When the frame halves are joined, the female end can be secured to the mount using a ¼ inch hitch pin inserted through a hole in the tee, outer tube, and inner tube.

Massaging Attachments:

A variety of attachments were developed to provide the user with a selection of massaging sensations.  These attachments included a hard knob, rubber ball, and massage roller ball, which were each fastened to their own threaded ¾ inch PCV plug so that they could be screwed into the threaded tee of the attachment mount.

Figure 5: Knob Attachment

  • The hard knob allows for a hard and small diameter massage. The hard knob is two separate pieces; the first piece is a red insert designed from SolidWorks and then printed from a Makerbot 3D printer, the second piece is a threaded ¾ inch to 1 inch PVC adapter.

Figure 6: Rubber Ball Attachment

  • The rubber ball allows for a soft pressure based massage which was formed from half of a lacrosse ball where the user can utilize rocking and rubbing motions to massage.

Figure 7: Roller Ball Attachment

  • The rolling ball allows for a large diameter rolling massage formed from a solid ball (similar to a billiard ball) and a casing which allows the ball to freely roll while the casing stays stationary.

The threaded plug allowed the attachments to be screwed into and out of the attachment mount at the back of the frame.  An acrylic baseplate, which was created to fit the octagonal head of the PVC plug, was fastened to the bottom of each attachment to prevent them from rotating around the center fastener.

Evaluation

Throughout the design, prototyping, and final construction phases, feedback and suggestions from professors, fellow students, clinicians, and the client were collected.  This information was then used to make appropriate modifications to our device.

The final device was evaluated to assess durability, client ease of use and comfort, device effectiveness, and portability.  The durability was assessed during the design phase and through testing to ensure that the frame could withstand the forces applied by the user.  Ease of use and comfort were judged during a one week trial period where the client documented her use of the device by filling out a daily log sheet. Following the trial period, the client completed a survey to evaluate the effectiveness of the device in relieving pain.  These surveys were also used to assess other aspects of the device, such as ease of use and portability, specifically the client’s ability to pack the device in a car or suitcase.

Discussion and Conclusions

In conclusion, the UMassage device met the project’s goals.  Unlike the client’s original massage solutions, such as tennis ball massage and massage chairs, UMassage can reach every square inch of the client’s back, and thus no “problem areas” go unaddressed. Plus, the client is able to keep her arms in front of her torso in a comfortable position, which is important because the client has said that she experiences some discomfort when having to reach for things (such as is needed with some other personal back massager devices).  Additionally, the feature of being able to use the device in any sort of seat provided to be very convenient for the client, as the client was able to use it in bed, in her armchair, and really anywhere she wanted to in her house or car.

The device provided a clear measure of pain relief to our client, as can be seen in the validation pre- and post-usage surveys taken by the client.  Over the course of the week that the client tested the device, her pain level showed a general downward trend, with the exception of a couple days, where strenuous activity in her life caused a spike in pain levels.  Although it is tough to determine the client’s quantitative long-term pain relief after only one week of device use, the client did say that the device provided fantastic temporary relief.  The roller ball attachment was her favorite, and she said that “the ball felt so good massaging the upper back.” The knob attachment, which was expected to be the best attachment for fibromyalgia patients due to its specific targeting feature, actually deemed to be too hard for the client.  In future iterations of the device, the knob attachment should be made out of a slightly softer material that can compress, such as rubber, whereby force is still applied to a very specific target point on the back.

UMassage also met the specifications of being lightweight and portable.  Its total weight with the heaviest attachment included (the roller ball) is 2.4 pounds, well under the target of 5 pounds.  The length of the device was also measured and found to be no larger than 2.5 feet in any dimension, as per the design specifications. The client loved how lightweight the device was and how easy it was for her to move from room to room with it.  As documented in her validation journal, she was able to use UMassage for time periods greater than the benchmark time of 20 minutes.  Thus, the device was lightweight enough so that no external support system was needed.  The portable UMassage travel model was created, which can be disassembled into two pieces, allowing her to bring the device with her in the car.  The assembly and disassembly of the travel frame, as well as changing the attachments, takes very little time and is easy to do.  The client did not have any problems with this, as her device setup time was well under the benchmark time of 5 minutes.

To evaluate safety and durability, we demonstrated that the device can withstand 20 pounds of force without deformation or failure, which is a realistic maximum force that the client can produce while massaging.  The device was lab verified with a safety factor of 2 to withstand 40 pounds of force.  Calculations were also done using the flexural properties of this type of PVC, giving a minimum breaking force of 3,400 pounds.  Thus, there is no way that the client could possibly deform or break the frame given the small loads she will be placing on the device.  The only major safety concern with this device is how you can easily bump your head on the attachment when first bringing the frame around your waste. However, no real medical harm can come from this, and over the time period of the client using the device, she will get used to avoiding this from happening.

Overall, UMassage met the design specifications and project goals.  Most importantly, it provided an essential pain-relieving tool that met all of the client’s needs.  One notable aspect to this project is how simple the design was, and thus how cheap the device was to produce.  Between using PVC, acrylic, 3D printer material, and screws, the cost for one model is under $30, which is far cheaper than many other massage solutions on the market.  Sometimes the simplest solution is the best solution.

References

[1] Mayo Clinic Staff. “Fibromyalgia.” Internet:http://www.mayoclinic.com/health/fibromyalgia/DS00079, Jan. 22, 2011 [Nov. 19, 2013].

[2] “Help Yourself Tennis Ball Self Massage.” Internet:http://help-yourself-techniques.blogspot.com/p/tennis-ball-self-massage.html, [Nov. 19, 2013].

[3] “Back Nodger.” Internet:http://www.backnodger.com/, [Nov. 19, 2013].

Acknowledgements

We’d like to thank our client for being so supportive and cooperative during the whole process.  We would also like to thank Dr. Be Na Lee, the clinician who worked with us during this process, as her input throughout the last couple of months was very helpful. We also want to acknowledge Dr. Michael Lee who allowed us to use his facilities in the early phase of the project to meet with the client.  Without them none of this would have been possible.  In addition, many thanks go out to the Department of Biomedical Engineering at UNC, as the suggestions we received from the faculty proved to be invaluable as we moved forward with our design; specifically Devin Hubbard, Kenneth Donnelly and Steve Emmanuel.  Lastly we would like to thank Dr. Richard Goldberg.  It was with his persistence and dedication to the class that allowed us to finish our design quickly and efficiently.  His guidance for the past year helped to keep us focused and on track and helped make the whole process much easier.  Now after the product has been designed, Dr. Goldberg is still helping us with all of our future steps, and we really appreciate all he has done for us.  Funding for this project was provided by  “National Science Foundation grant # CBET 0966571” for rehab projects.

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